[adam79]

On 8/29/10 9:42 AM, Sean Conolly wrote:

Also, although you may not be able to get rid of the ceiling tiles entirely,
you can still take out the tiles themselves, which will be a big
improvement. I've seen this done in a home tracking room, with the addition
of some fairly sheer fabric draped loosely across the ceiling. The
recordings I did there on drums don't have the comb filtering in the
overhead mics that you usually get with a low tile ceiling.


Just covering the tiles with a comforter, RockWool or Auralex Foam isn't
enough? Taking the tiles out (even if the material completely covers
them) makes a big difference?

The "mixing in my bedroom" comment, was a misprint/mistake on my part.
The living room is a rectangle. The celing tiles are in there as well..
one long wall is exposed brick, the other is wood paneling. One short
wall is drywall and the other is a large bay window with drywall under.

I can use a mic hooked up to the PA with a graphic equalizer to figure
out the natural room frequencies (so I can cut them out of the path
mic), right?

Thanks,
-Adam

[adam79]

This seems like a good deal:
http://jacksmusicstore.com/catalog/r...diofoam-2-burg.
4 square feet of Auralex foam for $15!

-Adam

[Scott Dorsey]

adam79 wrote:
Just covering the tiles with a comforter, RockWool or Auralex Foam isn't
enough? Taking the tiles out (even if the material completely covers
them) makes a big difference?

Rockwool does NOTHING at low frequencies. It is completely transparent.

The "mixing in my bedroom" comment, was a misprint/mistake on my part.
The living room is a rectangle. The celing tiles are in there as well..
one long wall is exposed brick, the other is wood paneling. One short
wall is drywall and the other is a large bay window with drywall under.

I can use a mic hooked up to the PA with a graphic equalizer to figure
out the natural room frequencies (so I can cut them out of the path
mic), right?

It would be a lot better to fix things.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[adam79]

On 8/29/10 7:44 PM, Scott Dorsey wrote:
wrote:
Just covering the tiles with a comforter, RockWool or Auralex Foam isn't
enough? Taking the tiles out (even if the material completely covers
them) makes a big difference?

Rockwool does NOTHING at low frequencies. It is completely transparent.


What about the Auralex Foam? The question I'm most interested in is if
the tiles still cause problems, even when completely covered w/ the
right material.

I can use a mic hooked up to the PA with a graphic equalizer to figure
out the natural room frequencies (so I can cut them out of the path
mic), right?

It would be a lot better to fix things.

I was talking about doing this once the room is treated.

Thanks,
-Adam

[Sean Conolly]

"adam79" wrote in message
news
On 8/29/10 9:42 AM, Sean Conolly wrote:

Also, although you may not be able to get rid of the ceiling tiles
entirely,
you can still take out the tiles themselves, which will be a big
improvement. I've seen this done in a home tracking room, with the
addition
of some fairly sheer fabric draped loosely across the ceiling. The
recordings I did there on drums don't have the comb filtering in the
overhead mics that you usually get with a low tile ceiling.


Just covering the tiles with a comforter, RockWool or Auralex Foam isn't
enough? Taking the tiles out (even if the material completely covers them)
makes a big difference?

The "mixing in my bedroom" comment, was a misprint/mistake on my part. The
living room is a rectangle. The celing tiles are in there as well.. one
long wall is exposed brick, the other is wood paneling. One short wall is
drywall and the other is a large bay window with drywall under.

In really basic terms, you're dealing with two main factors treating a
recording space: high frequemcy reflection and low frequency room nodes (aka
standing waves). The high frequency stuff causes comb filtering and flutter
if the room is really live. Auralex foam works fine on that problem, to both
absorb and diffuse the sound. So do a lot of other treatments.

The low frequency problem is harder to handle, because there's a lot of
energy in the low frequency sound, and you need either mass to absorb some
of the energy before it can reflect back into the room, or more space to
disipate it. In a small room there's not a lot of space, so you're left with
mass. In general, the heavier the treatment, the better the results will be
on low frequencies.


I can use a mic hooked up to the PA with a graphic equalizer to figure out
the natural room frequencies (so I can cut them out of the path mic),
right?

In a word, no. You simply can't EQ a bad a room into a good one, or even a
tolerable one.

I see in your other posts that you're looing at some nice mics, which is
good, but don't skimp on the room treatment. Using good mics in a bad
sounding room is not going to give the results you're paying for. That
doesn't mean you can't do it on a budget, you just need to do your homework
to get acceptable results.

Sean

[Scott Dorsey]

adam79 wrote:
On 8/29/10 7:44 PM, Scott Dorsey wrote:
wrote:
Just covering the tiles with a comforter, RockWool or Auralex Foam isn't
enough? Taking the tiles out (even if the material completely covers
them) makes a big difference?

Rockwool does NOTHING at low frequencies. It is completely transparent.

What about the Auralex Foam? The question I'm most interested in is if
the tiles still cause problems, even when completely covered w/ the
right material.

Zero, zilch, absolutely nil effect at low frequencies. Look at the datasheet.

I can use a mic hooked up to the PA with a graphic equalizer to figure
out the natural room frequencies (so I can cut them out of the path
mic), right?

It would be a lot better to fix things.

I was talking about doing this once the room is treated.

If the room is set up properly, you won't have to worry about room modes.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Ethan Winer[_3_]]

On Aug 29, 6:28 pm, adam79 wrote:
Just covering the tiles with a comforter, RockWool or Auralex Foam isn't
enough?

Many materials can absorb well at low frequencies. The key is how
thick they are, how large they are, and where you put them. The
standard for broadband bass traps is rigid fiberglass and rock wool /
mineral wool. But you need material that's at least four inches thick
for bass frequencies. If you add a paper or thin plastic membrane they
absorb bass even better. With such a suitable membrane you can get
good bass trapping even when it's only three inches thick. But thicker
is always better, and even six or eight inches (or thicker) is not too
much. Here are some links with general acoustics information:

Acoustic Basics:
http://www.realtraps.com/art_basics.htm

Much more detailed Acoustics FAQ:
http://www.ethanwiner.com/acoustics.html

--Ethan

[Cyberserf[_2_]]

On Aug 29, 10:33*pm, adam79 wrote:
On 8/29/10 7:44 PM, Scott Dorsey wrote:

*wrote:
Just covering the tiles with a comforter, RockWool or Auralex Foam isn't
enough? Taking the tiles out (even if the material completely covers
them) makes a big difference?

Rockwool does NOTHING at low frequencies. *It is completely transparent.

[adam79]

On 8/30/10 9:00 AM, Scott Dorsey wrote:

What about the Auralex Foam? The question I'm most interested in is if
the tiles still cause problems, even when completely covered w/ the
right material.

Zero, zilch, absolutely nil effect at low frequencies. Look at the datasheet.


I want to focus on the room acoustics for the drums at the current
moment. I skimmed through the links Ethan gave me (I'll have a chance to
read it all tonight) and came up with the following.. If I remove the
tiles and replace them with dense fiberglass material (i.e.
Owens-Corning 703 or 705), then cover the fiberglass with Guilford FR701
(or something equivalent since FR701 is expensive), will I need a third
material to cover the FR701 to complete the ceiling treatment?

Once I have figured out a plan for the ceiling, I will move onto bass
traps for the corners.

Thanks,
-Adam

[Scott Dorsey]

In article ,
adam79 wrote:
On 8/30/10 9:00 AM, Scott Dorsey wrote:

What about the Auralex Foam? The question I'm most interested in is if
the tiles still cause problems, even when completely covered w/ the
right material.

Zero, zilch, absolutely nil effect at low frequencies. Look at the datasheet.

I want to focus on the room acoustics for the drums at the current
moment. I skimmed through the links Ethan gave me (I'll have a chance to
read it all tonight) and came up with the following.. If I remove the
tiles and replace them with dense fiberglass material (i.e.
Owens-Corning 703 or 705), then cover the fiberglass with Guilford FR701
(or something equivalent since FR701 is expensive), will I need a third
material to cover the FR701 to complete the ceiling treatment?

Take the drop ceiling out. The drop ceiling causes problems that are
different and not related to the fact that it's absorptive in the midrange
and not the low end.

Once I have figured out a plan for the ceiling, I will move onto bass
traps for the corners.

How will that help when you have a huge partially-sealed chamber with a
massive bass resonance in your ceiling?
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[adam79]

On 8/30/10 3:34 PM, Scott Dorsey wrote:

Take the drop ceiling out. The drop ceiling causes problems that are
different and not related to the fact that it's absorptive in the midrange
and not the low end.


A quick question on absorption. I understand that I need to absorb
reflections. As far as frequencies go, I not exactly sure what the goal
is, as I'm just beginning to read up on acoustical treatments. Are there
certain frequencies you want to keep in the room, rather than absorbing
everything. If there is an article about this topic that I missed along
the way, please send me a link.

Thanks,
-Adam

[Mike Rivers]

adam79 wrote:

A quick question on absorption. I understand that I need to absorb
reflections.

Actually, what you want to absorb is the direct sound that
would hit a reflective surface to prevent it from becoming a
reflection.

As far as frequencies go, I not exactly sure what the goal
is, as I'm just beginning to read up on acoustical treatments. Are there
certain frequencies you want to keep in the room, rather than absorbing
everything.

Not really. You want the absorbers to absorb equally over as
wide a frequency range as you can afford. If your absorbers
only work at high frequencies, your room will sound boomy,
because the low frequency reflections will still be present.
But you want to reduce, not totally eliminate reflections,
in the "presence" range so that it won't sound to the singer
or player like he's in a totally dead room. This is why
absorbers often don't cover the full surface, but there are
some untreated areas (the location and size determined by
both trigonometry and experimentation) that provide a
little liveness but with little enough energy to not create
comb filtering at the microphones.

Surely there must be something about this on Ethan Winer's
website, http://www.realtraps.com



--
"Today's production equipment is IT based and cannot be
operated without a passing knowledge of computing, although
it seems that it can be operated without a passing knowledge
of audio." - John Watkinson

[Scott Dorsey]

adam79 wrote:
On 8/30/10 3:34 PM, Scott Dorsey wrote:

Take the drop ceiling out. The drop ceiling causes problems that are
different and not related to the fact that it's absorptive in the midrange
and not the low end.

A quick question on absorption. I understand that I need to absorb
reflections.

NO! YOU CANNOT ABSORB LOW FREQUENCY REFLECTIONS! I keep saying this over
and over again to you.

As far as frequencies go, I not exactly sure what the goal
is, as I'm just beginning to read up on acoustical treatments. Are there
certain frequencies you want to keep in the room, rather than absorbing
everything. If there is an article about this topic that I missed along
the way, please send me a link.

You want the general room response to remain flat. The hard part is dealing
with the low end. Once you have dealt with the low end, you will probably
find you don't have _enough_ reflectance in the room at high frequencies.

Deal with the low end, then worry about absorption and diffusion later on
once the low end is under control, in order to get the high frequency
reverberation to match the low frequency.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Ethan Winer[_3_]]

On Aug 31, 1:28 am, adam79 wrote:
A quick question on absorption. I understand that I need to absorb
reflections. As far as frequencies go, I not exactly sure what the goal
is, as I'm just beginning to read up on acoustical treatments.

The type of "early" and "first" reflections you get from side-walls
and the ceiling are mainly damaging at mid and high frequencies.
That's the range that affects imaging and clarity. When those
reflections are absorbed you can better hear small changes in EQ and
panning and reverb effects. But Mike and Scott are of course correct
too - the general goal for absorption in a room is to be *broadband*.
Mike's comment to absorb "over as wide a frequency range as you can
afford" is a perfect way to put it.

Are there certain frequencies you want to keep in the room, rather
than absorbing everything.

It doesn't really work that way. Besides wanting a uniform frequency
response, you also want a uniform RT60 (reverb decay time). How long a
decay is acceptable depends on the size of the room. For smaller
domestic size rooms you should aim for no obvious reverb or ambience.
So it's not like it's okay to have lots of reflection at some
frequencies but not at others.

--Ethan

[Frank Stearns]

Ethan Winer writes:

On Aug 31, 1:28 am, adam79 wrote:
A quick question on absorption. I understand that I need to absorb
reflections. As far as frequencies go, I not exactly sure what the goal
is, as I'm just beginning to read up on acoustical treatments.

The type of "early" and "first" reflections you get from side-walls
and the ceiling are mainly damaging at mid and high frequencies.
That's the range that affects imaging and clarity. When those
reflections are absorbed you can better hear small changes in EQ and
panning and reverb effects. But Mike and Scott are of course correct
too - the general goal for absorption in a room is to be *broadband*.
Mike's comment to absorb "over as wide a frequency range as you can
afford" is a perfect way to put it.

Well, within limits.... For the reasons you state you do want to kill early
reflections as much as possible, but you don't want a completely anechoic room. That
can get weird and even misleading.

I posted a reply to Adam that was meant to add to this thread but it got emailed by
mistake.

I'd suggested a review of the F. Alton Everest books, "Master Handbook of
Acoustics" and "Sound Studio Construction on a Budget".

Are there certain frequencies you want to keep in the room, rather
than absorbing everything.

It doesn't really work that way. Besides wanting a uniform frequency
response, you also want a uniform RT60 (reverb decay time). How long a
decay is acceptable depends on the size of the room. For smaller
domestic size rooms you should aim for no obvious reverb or ambience.
So it's not like it's okay to have lots of reflection at some
frequencies but not at others.

What we found here (and love very much) in a small room is an RT30 of 120 mSec
below 200 hz, rising gradually (with no spikes in the time) to about 1 second
10Khz.

We got this through a combination of many panel traps, absorption, diffusion, and
even some very narrow and controlled reflections. It really is a great room to work
in. While it didn't take a huge amount of money, it took some basic calculations,
followed by a lot of trial and error. Well worth it. Everest and a simple
measurement system (MLS-based) proved useful tools.

Frank


--

[adam79]

On 8/31/10 2:43 PM, Frank Stearns wrote:

What we found here (and love very much) in a small room is an RT30 of120 mSec
below 200 hz, rising gradually (with no spikes in the time) to about 1 second
10Khz.

We got this through a combination of many panel traps, absorption, diffusion, and
even some very narrow and controlled reflections. It really is a great room to work
in. While it didn't take a huge amount of money, it took some basic calculations,
followed by a lot of trial and error. Well worth it. Everest and a simple
measurement system (MLS-based) proved useful tools.


The big word in your post is "money." I only have a couple hundred
dollars in my budget for acoustical treatment. I realize the extreme
importance in room acoustics; I've put a halt to any other purchase
unrelated to this topic. I took a couple pictures of the room I plan to
record in. It's cluttered, but you can get the idea. I put them all in
one photobucket album:
http://s273.photobucket.com/albums/j...l%20Treatment/.
I also included the floor plan I drew up (which I failed [more like
forgot] to drawn to scale). So if I title a picture "Left End," it means
it's located at the left of the floor plan, and etc.

It was recommended to me by someone on this group to put the drum set in
the corner. Do you think it would be a better idea to put it where the
amps are (so the drummers back would be facing the wall)?

Thanks,
-Adam

[Scott Dorsey]

adam79 wrote:
The big word in your post is "money." I only have a couple hundred
dollars in my budget for acoustical treatment. I realize the extreme
importance in room acoustics; I've put a halt to any other purchase
unrelated to this topic.

Then, look at Ethan's homemade bass traps. Build some. Deal with your
low end problems first, because everything else is cheap and easy in
comparison.

It was recommended to me by someone on this group to put the drum set in
the corner. Do you think it would be a better idea to put it where the
amps are (so the drummers back would be facing the wall)?

Go in and use your ears and listen to what it sounds like. Do you hear
clanging sounds? If you put your finger in one ear and walk around the
room, does the kick drum sound dramatically different in two places a
foot away? If you clap your hands, it it hollow? Do you hear individual
slaps or does the sound decay evenly? Your ears are the best tool to
find out what is wrong with the room so you know what to fix.

I can make some pretty good guesses about what you're going to hear and
they're going to be pretty scary on the bottom end, but there is no
substitute for listening.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Mike Rivers]

adam79 wrote:

The big word in your post is "money." I only have a couple hundred
dollars in my budget for acoustical treatment.

This could be a problem. How much do you have (or have you
already spent) on microphones, monitor speakers, A/D
converters, and the like? There's no point in having a
$3,000 set of monitors if you can't accurately hear what's
coming out of them.

It was recommended to me by someone on this group to put the drum set in
the corner. Do you think it would be a better idea to put it where the
amps are (so the drummers back would be facing the wall)?

When I suggested setting the drums in the corner, I meant to
include the drummer. He should be in the corner, facing the
center of the room, with the drums in playable position in
front of him. Maybe. What this does is puts the reflecting
walls fairly close to the drums so that early reflections
will be pretty close to in phase with the direct sound. On a
budget that allows only a couple of hundred bucks for
acoustic treatment, you probalby aren't going to be
close-miking each drum, so you're going to be recording
reflections. Might as well take advantage of them as fight
them.


--
"Today's production equipment is IT based and cannot be
operated without a passing knowledge of computing, although
it seems that it can be operated without a passing knowledge
of audio." - John Watkinson

[Frank Stearns]

adam79 writes:

On 8/31/10 2:43 PM, Frank Stearns wrote:

What we found here (and love very much) in a small room is an RT30 of120 mSec
below 200 hz, rising gradually (with no spikes in the time) to about 1 second
10Khz.

We got this through a combination of many panel traps, absorption, diffusion, and
even some very narrow and controlled reflections. It really is a great room to work
in. While it didn't take a huge amount of money, it took some basic calculations,
followed by a lot of trial and error. Well worth it. Everest and a simple
measurement system (MLS-based) proved useful tools.


The big word in your post is "money." I only have a couple hundred
dollars in my budget for acoustical treatment. I realize the extreme
importance in room acoustics; I've put a halt to any other purchase
unrelated to this topic. I took a couple pictures of the room I plan to
record in. It's cluttered, but you can get the idea. I put them all in


Certainly a challenge. The bad news is the low ceiling. The not as bad news is that
it doesn't appear that you're doing movie scoring or classical recording. You can
thus close mic everything (you probably would regardless of the room) and minimize
room issues, though you certainly want to experiement with room mics -- who knows,
you might find a sweet spot that will really bring amps and drums to life when
blended under the close mics.

For acoustical treatment, you can actually do some useful bits with that $200 if
you're handy with trim saw or even a hand saw if you're careful. You need a bundle
of Owens-Corning 703 unfaced pressed fiberglass insulation (probably $90-$110, if
you can find a wholesaler to sell it to you). IIRC, there are 20 sheets in that
bundle. Four will be used for the "springs" inside the absorbers (one sheet each),
the rest can be stacked in 2" and 3" configurations, faced with inexpensive cloth
(but listen "through" the cloth you select to make sure it's relatively transparent
acoustically). Placed those stacks as MF and HF absorbers as needed. Float those out
from the wall 2-4" to nearly double their effectiveness.

48 feet of KD 2x4 framing lumber will let you build the frames for four 2'x4' panel
traps, good for 50-120 hz absorption. Figure $12. A sheet of 1/4" ACX plywood will
work for the four diaphragms - $15. For a couple of bucks most yards will cut the
sheet into four 2'x4' panels for you. (You'll wind up trimming down the 703 panels a
bit to fit the *inside* of a frame where the *outside* dimensions are probably 24"
by 48" so that you don't wind up wasting a lot of 2x4.)

Figure another $10 for caulk or closed-cell weather stripping (I prefer the latter
because it makes the absorbers more removable), lag bolts, and smaller screws to
attach the 1/4" panels to the frames built from the 2x4s, which you've lag-bolted to
the wall. Lags are countersunk so that they won't interfere with the top panel.
Don't overtighten lags or panel screws; you want "softer" tension so that the trap
itself doesn't start "singing" because it's been tensioned like a piano string.

Do not bypass the weather stripping frame-to-wall and panel-to-wall. Panel traps
*MUST* be air-tight to work (see Everest for more details). Caulk the frame joints.

So at this point we're close to $200. So far, so good.

Where to put the traps is the question. In a room with that many changes in relief
it will be a little more difficult decision to make. (But in some ways, the somewhat
jagged changes in dimensions might help break up some of the modes.)

If you've worked a lot with pink noise and can hear the resonances, you can fill the
room with it and simply listen for resonances by moving around the boundaries,
seeing where you start getting bass tones climbing out of the noise. Alternately,
you can sweep sine waves from 40-100 hz and see where things really stick out. Don't
play the tones or the pink noise too loud, you'll quickly "funnel" your ears.

Expect issues around 160 Hz because of the 7'2" ceiling. You might even wind up
building some resonators to go after that aread -- cheap to do with MDF, concrete
form tube, and 3" PVC drain pipe.

Again, Evererst has some ideas on all this. Ideal if you can get your hands on some
ETF (energy-time-frequency) measurement tools. Careful with a plain old 1/3 octave
analyzer. It won't really tell you where the problems might be.

And, as Scott suggested, a finger in one ear while listening to instruments can be
useful, but often it takes a very experienced listener to make sense of what's being
heard in that mode.

Now, with the HF and MF frequencies, placement of those absorbers is a little
easier. Find the the flutter echos and plop an absorber there. Clapping your hands
will tell you a lot; I love my dog clickers (available at most any pet store for
$2). It makes a nice pair of spike clicks -- flutter echos, funny decays (or good
decays) are then readily evident. (We do location work; I walk each new room with
the clicker -- you'd be amazed at what can be revealed. Saved my bacon more than
once.)

Sigh. Like I said, this can get fairly complex rather quickly. Study Everest.

I (and probably many here) admire your attention to this detail. You'll probably get
frustrated at some point, but stay with it.

Frank
Mobile Audio
--

[adam79]

On 8/31/10 9:27 PM, Mike Rivers wrote:
adam79 wrote:

The big word in your post is "money." I only have a couple hundred
dollars in my budget for acoustical treatment.

This could be a problem. How much do you have (or have you already
spent) on microphones, monitor speakers, A/D converters, and the like?
There's no point in having a $3,000 set of monitors if you can't
accurately hear what's coming out of them.


Like I've been saying, I'm in the process now of planning on how to
spend my money to start this home studio. For recording I have Pro Tools
w/ a MBox2 and Korg D16 Multitrack (that I use with the MBox2 SPDIF
connection). For mics I just have 2 MCA SP1s, 1 SM57 and 1 SM87. I have
M-Audio BX5a monitors. I know they're low-end, but I talked a friend
into selling them to me for $100; they were just gathering dust with him.
For jamming, I have a Mackie 1202 VLZ-PRO mixer (that's old and starting
to die), a QSC RMX 2450 power amp and a pair of JBL MPro MP215 speakers.
I was planning on buying a new mixer, but after starting this thread, I
realize that I need to focus on the room acoustics first.


When I suggested setting the drums in the corner, I meant to include the
drummer. He should be in the corner, facing the center of the room, with
the drums in playable position in front of him. Maybe. What this does is
puts the reflecting walls fairly close to the drums so that early
reflections will be pretty close to in phase with the direct sound. On a
budget that allows only a couple of hundred bucks for acoustic
treatment, you probalby aren't going to be close-miking each drum, so
you're going to be recording reflections. Might as well take advantage
of them as fight them.


I don't have enough mics to close mic anyways. My initial plan is to put
up the two SP1s as overheads, a RE20 or MD421 (I'm gonna rent a couple
mics) on the kick and a SM57 on the snare. I also might try some 3 mic
techniques I've used in the past (with good results), and others that I
read about in a Mercenary Audio article. I wanted to rent a Beyer M160
for the 3 mic scenario, but the only ribbon mic the rental place has is
a Samson V88 (which I've never used; the reviews I've read are mixed).

Like I've been saying, most of my clients will be local punk/hardcore
bands. They typically like more raw recordings than the highly processed
mainstream sound. However, this doesn't mean I can skimp on the room
treatment. I want to do everything within my means (budget) to make
everything to sound it's best.

Thanks,
-Adam

[WillStG]

On Aug 31, 10:57*pm, Frank Stearns
wrote:
adam79 writes:
On 8/31/10 2:43 PM, Frank Stearns wrote:

What we found here (and love very much) in a small room is an RT30 of120 mSec
below 200 hz, rising gradually (with no spikes in the time) to about 1 second
10Khz.

We got this through a combination of many panel traps, absorption, diffusion, and
even some very narrow and controlled reflections. It really is a great room to work
in. While it didn't take a huge amount of money, it took some basic calculations,
followed by a lot of trial and error. Well worth it. Everest and a simple
measurement system (MLS-based) proved useful tools.

The big word in your post is "money." I only have a couple hundred
dollars in my budget for acoustical treatment. I realize the extreme
importance in room acoustics; I've put a halt to any other purchase
unrelated to this topic. I took a couple pictures of the room I plan to
record in. It's cluttered, but you can get the idea. I put them all in

Certainly a challenge. The bad news is the low ceiling. The not as bad news is that
it doesn't appear that you're doing movie scoring or classical recording. You can
thus close mic everything (you probably would regardless of the room) and minimize
room issues, though you certainly want to experiement with room mics -- who knows,
you might find a sweet spot that will really bring amps and drums to life when
blended under the close mics.

For acoustical treatment, you can actually do some useful bits with that $200 if
you're handy with trim saw or even a hand saw if you're careful. You need a bundle
of Owens-Corning 703 unfaced pressed fiberglass insulation (probably $90-$110, if
you can find a wholesaler to sell it to you). IIRC, there are 20 sheets in that
bundle. Four will be used for the "springs" inside the absorbers (one sheet each),
the rest can be stacked in 2" and 3" configurations, faced with inexpensive cloth
(but listen "through" the cloth you select to make sure it's relatively transparent
acoustically). Placed those stacks as MF and HF absorbers as needed. Float those out
from the wall 2-4" to nearly double their effectiveness.

48 feet of KD 2x4 framing lumber will let you build the frames for four 2'x4' panel
traps, good for 50-120 hz absorption. Figure $12. A sheet of 1/4" ACX plywood will
work for the four diaphragms - $15. For a couple of bucks most yards will cut the
sheet into four 2'x4' panels for you. (You'll wind up trimming down the 703 panels a
bit to fit the *inside* of a frame where the *outside* dimensions are probably 24"
by 48" so that you don't wind up wasting a lot of 2x4.)

Figure another $10 for caulk or closed-cell weather stripping (I prefer the latter
because it makes the absorbers more removable), lag bolts, and smaller screws to
attach the 1/4" panels to the frames built from the 2x4s, which you've lag-bolted to
the wall. Lags are countersunk so that they won't interfere with the top panel.
Don't overtighten lags or panel screws; you want "softer" tension so that the trap
itself doesn't start "singing" because it's been tensioned like a piano string.

Do not bypass the weather stripping frame-to-wall and panel-to-wall. Panel traps
*MUST* be air-tight to work (see Everest for more details). Caulk the frame joints.

So at this point we're close to $200. So far, so good.

Where to put the traps is the question. In a room with that many changes in relief
it will be a little more difficult decision to make. (But in some ways, the somewhat
jagged changes in dimensions might help break up some of the modes.)

If you've worked a lot with pink noise and can hear the resonances, you can fill the
room with it and simply listen for resonances by moving around the boundaries,
seeing where you start getting bass tones climbing out of the noise. Alternately,
you can sweep sine waves from 40-100 hz and see where things really stick out. Don't
play the tones or the pink noise too loud, you'll quickly "funnel" your ears.

Expect issues around 160 Hz because of the 7'2" ceiling. You might even wind up
building some resonators to go after that aread -- cheap to do with MDF, concrete
form tube, and 3" PVC drain pipe.

Again, Evererst has some ideas on all this. Ideal if you can get your hands on some
ETF (energy-time-frequency) measurement tools. Careful with a plain old 1/3 octave
analyzer. It won't really tell you where the problems might be.

And, as Scott suggested, a finger in one ear while listening to instruments can be
useful, but often it takes a very experienced listener to make sense of what's being
heard in that mode.

Now, with the HF and MF frequencies, placement of those absorbers is a little
easier. Find the the flutter echos and plop an absorber there. Clapping your hands
will tell you a lot; I love my dog clickers (available at most any pet store for
$2). It makes a nice pair of spike clicks -- flutter echos, funny decays (or good
decays) are then readily evident. (We do location work; I walk each new room with
the clicker -- you'd be amazed at what can be revealed. Saved my bacon more than
once.)

Sigh. Like I said, this can get fairly complex rather quickly. Study Everest.

I (and probably many here) admire your attention to this detail. You'll probably get
frustrated at some point, but stay with it.

Frank
Mobile Audio
--
*.

Adam, great practical advice from Frank. And you can download a
free room analysis tool that can help you figure out exactly what is
going on with your space at http://www.hometheatershack.com/roomeq/.
They have mac and PC versions. I wouldn't try to use eq on my room
like they do in Home Theatre though.

Build the broadband absorption panels, and place them as Ethan
recommends on his website. Do remove the ceiling tiles, and put some
up there. I'd read up about room design as much as you can, since the
rest will be a "shotgun", trail and error approach. I like "Live end/
dead end" design; make the room pretty dead behind the speakers and
diffuse the opposite wall behind your mixing position. Bookshelves can
be a cheap method for diffusion, and the couch back there helps absorb
the floor corner reflection. In the recording area, if you have any
cabinets in there for storage, angle them so they aren't parallel to
the wall. I have seen studios with built in storage cabinets, the
doors all angled in different directions like 5 or 6 inches, sometimes
making pairs of doors kinda trapezopidal. You also probably need to
build some gobos for the recording area, 4'x8' boxes stuffed with
fiberglass, one side exposed fabric the other side wood. Use light
wood, even luan.

You have to get used to figuring out what is reflecting where, and
prevent as much of that as possible. Not just in how your room is set
up, but in the recording process too. Where amps and instruments face
and where the mics are placed is important, it's all related. Because
you don't have a good open sounding room the drums will sound a bit
constricted, that's what happens when you rely on the close mics. I
like to catch some of the overall kit in the overheads, I try to get
cymbals close, hat/toms a bit next, and finally snare (they point at
the snare.) But if the room sounds bad you may have to just mic the
cymbals. In which case omni mics can be useful in creating a more
open sound, maybe a pair of cheap Behringer ECM8000's on your budget
(like $50 ea maybe.) You can also use an ECM8000 as a measurement mic
with the room analysis software. You might also research using a
blanket tunnel around the kick drum so the room doesn't get saturated
with the kick's lows. Keeping that out of the overheads might help
you.

As for the original question about "Sound boards". I have to
say, the Tascam DM4800 is a giant killer (sorry giants). $5500 with a
meter bridge and a firewire card. Over firewire it will do 32 channels
to any DAW except Pro Tools. It has 24 motorized faders for automated
mixing, 24 micpres, 8 auxes, 48 full featured channels, 64 total
channels on mix down, and will give you 24 fader control of Pro Tools
(or Logic, Cubase etc.). You can route any input to any output. It
has 4 expansion slots for adding more analog or digital I/O, or the
firewire card, and a cascade port built in for using 2! DM4800's
together. It sounds very very good. At 24/48k, I like it's
converters better than Pro Tools HD's 96 I/O. If you want to do this
for a long time it is well worth the investment, it's worth much more
than it sells for - and it's light enough to move by yourself.

Good luck.

Will Miho
NY TV/Audio Post/Music/Live Sound Guy
"The large print giveth and the small print taketh away..." Tom Waits

[Frank Stearns]

Frank Stearns writes:

Oops. Brain slower than fingers in a few places in my previous posts about your
room acoustics. A few corrections:

Regarding the Owens-Corning 703 used for the absorbers and panel traps. It comes in
thicknesses of 1", 2", and 3". I was referring to the 1" variety -- a flexible
format for your needs and budget.

703 is 3 lbs per cubic foot; 705 is 6 lbs per cubic foot. The latter can be a little
better in some respects, but is way more expensive (and harder to find).

Make sure you get it unfaced. (It can be purchased with one or both sides faced with
a thick aluminum foil sheeting -- not what you want).

The panel traps use a single 1" thickness just under (but not touching) the plywood
diaphragm, with air space for the remaining thickness of the trap. Weatherstripping
goes between the panel and frame, and then the frame and wall.

Once done with the traps, you can sandwich 1" sheets to make 2" and 3" absorbers;
I've used automotive spray glue to tack the layers together, with a cloth wrap for
the final binding.

Do not leave this stuff exposed. It won't burn but it will shed fine particles.
Supposedly, such particles are more or less benign, but I sure as heck don't want
to breath little micro-shards of glass floating in the air. (There are warnings on
the package, as I recall.)

Handle with gloves and long-sleeve shirts. You'll itch otherwise.

Have fun!

Frank
Mobile Audio

--

[adam79]

Thanks for all the help. I've been talking with a guy at Acoustical
Services, and he recommended this stuff called "Echo Eliminator," here's
the link:
http://www.acousticalsurfaces.com/ec..._panel.htm?d=0.
It's absorption rating for low frequencies is decent (great when
compared to other materials). Does anyone have any experience using the
"Echo Eliminator?"

Thanks,
-Adam

On 9/1/10 12:43 PM, Frank Stearns wrote:
Frank writes:

Oops. Brain slower than fingers in a few places in my previous posts about your
room acoustics. A few corrections:

Regarding the Owens-Corning 703 used for the absorbers and panel traps. It comes in
thicknesses of 1", 2", and 3". I was referring to the 1" variety -- a flexible
format for your needs and budget.

703 is 3 lbs per cubic foot; 705 is 6 lbs per cubic foot. The latter can be a little
better in some respects, but is way more expensive (and harder to find).

Make sure you get it unfaced. (It can be purchased with one or both sides faced with
a thick aluminum foil sheeting -- not what you want).

The panel traps use a single 1" thickness just under (but not touching) the plywood
diaphragm, with air space for the remaining thickness of the trap. Weatherstripping
goes between the panel and frame, and then the frame and wall.

Once done with the traps, you can sandwich 1" sheets to make 2" and 3" absorbers;
I've used automotive spray glue to tack the layers together, with a cloth wrap for
the final binding.

Do not leave this stuff exposed. It won't burn but it will shed fine particles.
Supposedly, such particles are more or less benign, but I sure as heck don't want
to breath little micro-shards of glass floating in the air. (There are warnings on
the package, as I recall.)

Handle with gloves and long-sleeve shirts. You'll itch otherwise.

Have fun!

Frank
Mobile Audio

[Frank Stearns]

adam79 writes:

Thanks for all the help. I've been talking with a guy at Acoustical
Services, and he recommended this stuff called "Echo Eliminator," here's
the link:
http://www.acousticalsurfaces.com/ec..._panel.htm?d=0.
It's absorption rating for low frequencies is decent (great when
compared to other materials). Does anyone have any experience using the
"Echo Eliminator?"

Have not heard of these folks, but the product sounds good, and it would save you
some steps. Is it within your budget? I didn't see pricing info, but might have
missed it.

Does anyone carry it locally where you can go see it and do a little tire-kicking?

One vague but somewhat useful test is to put your ear 4-6" inches from anything that
is supposed to be an absorber. The good stuff (for absorption, such as the 703),
makes you a little queasy because there is *nothing* coming back from it. You almost
feel as if you're going to "fall" into nothingness. If effective as an absorber,
this stuff should do something similar.

Also, assuming the specs are accurate, it would probably provide a little extra help
with the 160 Hz issue you'll likely have because of the ceiling height.

But, like all such products, including 703 and to slightly lesser degree 705, best I
could tell it won't do much below 125 Hz. For the next octave down, you'd still need
panel traps. The 4" product is no doubt a little better with bass control, but still
probably can't compare to a panel trap.

I too will be interested if anyone here has any experience with this material.

Frank
Mobile Audio

--

[Scott Dorsey]

Ethan Winer wrote:

The type of "early" and "first" reflections you get from side-walls
and the ceiling are mainly damaging at mid and high frequencies.
That's the range that affects imaging and clarity. When those
reflections are absorbed you can better hear small changes in EQ and
panning and reverb effects. But Mike and Scott are of course correct
too - the general goal for absorption in a room is to be *broadband*.
Mike's comment to absorb "over as wide a frequency range as you can
afford" is a perfect way to put it.

I think it's bad to think of a bass trap as an absorber. It doesn't really
_absorb_ low frequencies in the way that people think. It's also not a
resonator. It's something different.

It doesn't really work that way. Besides wanting a uniform frequency
response, you also want a uniform RT60 (reverb decay time). How long a
decay is acceptable depends on the size of the room. For smaller
domestic size rooms you should aim for no obvious reverb or ambience.
So it's not like it's okay to have lots of reflection at some
frequencies but not at others.

I think in small rooms, talking about RT60 very quickly becomes useless,
but I wish I had a better way to talk about reverb decay in small rooms.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Ethan Winer[_3_]]

On Sep 2, 9:30 am, (Scott Dorsey) wrote:
I think it's bad to think of a bass trap as an absorber. It doesn't really
_absorb_ low frequencies in the way that people think. It's also not a
resonator. It's something different.

Well first, there are several types of bass traps. The most common
type is based on a "porous" absorber such as fiberglass, mineral wool,
acoustic (open cell) foam, or even recycled denim. This type of bass
trap absolutely "absorbs" sound waves. You can see the proof of
absorption not only in improved Before / After frequency response
graphs, but also waterfall plots that show a reduction in decay times.
The only way such improvements are achieved is to reduce the strength
of reflections. And the only way I know of to reduce reflections -
other than opening a window to the outdoors - is to absorb them. So
there's no question that bass traps work via absorption.

I think in small rooms, talking about RT60 very quickly becomes useless, but I wish I had a better way to talk about reverb decay in small rooms.

Yes, RT60 is meaningless in most small rooms. If a room is totally
empty you can have a long enough decay over time to call it "reverb."
But even then, the decays vary by frequency. The longest decays occur
at the "flutter echo" frequencies, which in turn are related to the
room dimensions.

There is a better metric, at least as applied to playback rooms. I
suppose it could be used in recording rooms too. That metric is called
an Energy Time Curve, and it shows the strength of individual
reflections over time. This is a great way to spot early reflections
in a control room, and see if they're string enough to cause severe
comb filtering. Most room measurement programs can show an ETC graph.
For example, the freeware Room EQ Wizard program I use these days does
that:

http://www.hometheatershack.com/roomeq/

--Ethan

[Frank Stearns]

(Scott Dorsey) writes:

Ethan Winer wrote:

The type of "early" and "first" reflections you get from side-walls
and the ceiling are mainly damaging at mid and high frequencies.
That's the range that affects imaging and clarity. When those
reflections are absorbed you can better hear small changes in EQ and
panning and reverb effects. But Mike and Scott are of course correct
too - the general goal for absorption in a room is to be *broadband*.
Mike's comment to absorb "over as wide a frequency range as you can
afford" is a perfect way to put it.

I think it's bad to think of a bass trap as an absorber. It doesn't really
_absorb_ low frequencies in the way that people think. It's also not a
resonator. It's something different.

I've thought of them as small springs attached to a bring spring. The LF energy in
the room is the big spring, and as it begins to undulate at the various mode
frequencies the small springs, the panel traps, pick off a portion of that engery as
it rolls through the big spring. The energy is not returned to the big spring, so it
(the room) does not "boing" (resonate) as much in the low end.

The 1" 703 behind the diaphragm in the trap is a shock absorber, and moderates
rebound flex of the diaphragm, working with the air pocket in the trap (one of the
reasons air tightness in the trap is so important).

Diaphragm mass, tension, area, and trap depth set the Q and center frequency of the
trap. (There's nothing very narrow about this, but you can nudge the effective band
a little in either direction.)

Some or all the above might be incorrect; I'm up for any better explanations.


I think in small rooms, talking about RT60 very quickly becomes useless,
but I wish I had a better way to talk about reverb decay in small rooms.

Yes, quite true. My MLS system offers RT20 and 30, which seem to have more value in
a small room. (I hope I cited RT30 values when I noted our room's response.)

Makes more sense to measure the width of your front door with a yardstick rather
than with the odometer in your car.

Frank
Mobile Audio

--

[Don Pearce[_3_]]

On Thu, 02 Sep 2010 11:27:10 -0500, Frank Stearns
wrote:

(Scott Dorsey) writes:

Ethan Winer wrote:

The type of "early" and "first" reflections you get from side-walls
and the ceiling are mainly damaging at mid and high frequencies.
That's the range that affects imaging and clarity. When those
reflections are absorbed you can better hear small changes in EQ and
panning and reverb effects. But Mike and Scott are of course correct
too - the general goal for absorption in a room is to be *broadband*.
Mike's comment to absorb "over as wide a frequency range as you can
afford" is a perfect way to put it.

I think it's bad to think of a bass trap as an absorber. It doesn't really
_absorb_ low frequencies in the way that people think. It's also not a
resonator. It's something different.

I've thought of them as small springs attached to a bring spring. The LF energy in
the room is the big spring, and as it begins to undulate at the various mode
frequencies the small springs, the panel traps, pick off a portion of that engery as
it rolls through the big spring. The energy is not returned to the big spring, so it
(the room) does not "boing" (resonate) as much in the low end.

The 1" 703 behind the diaphragm in the trap is a shock absorber, and moderates
rebound flex of the diaphragm, working with the air pocket in the trap (one of the
reasons air tightness in the trap is so important).

Diaphragm mass, tension, area, and trap depth set the Q and center frequency of the
trap. (There's nothing very narrow about this, but you can nudge the effective band
a little in either direction.)

Some or all the above might be incorrect; I'm up for any better explanations.


I think in small rooms, talking about RT60 very quickly becomes useless,
but I wish I had a better way to talk about reverb decay in small rooms.

Yes, quite true. My MLS system offers RT20 and 30, which seem to have more value in
a small room. (I hope I cited RT30 values when I noted our room's response.)

Makes more sense to measure the width of your front door with a yardstick rather
than with the odometer in your car.

Frank
Mobile Audio
You really can't think of absorbers as springs. Springs do not absorb
energy - they give back all of it. If they give it back with delay,
they are a huge problem. If they give it back with no delay, they are
purely elastic surfaces - tiles would be a good example. To kill
flutter echoes in a room, you have no choice - the energy must not be
returned along its incident path. You either absorb it, or let it out
into the outside where it can radiate. Both do an identical job, but
obviously with the second you do let the outside noise in.

You are absolutely right about the 703 being a shock absorber.
Absorbing and dissipating energy is precisely what a shock absorber
does.

RT20 and RT30 are no better than RT60 in small rooms. What they do is
offer a spec which can be verified in a reasonably noisy environment.
If you have an RT60 curve for a room, you can read the RT20 and RT30
values straight off it. Taming a small room is really hard. You need
to think about what you are doing in the room. Voiceover work is
simple, and "intimate" small instruments that don't mind being
close-miked are a possibility.

d

[adam79]

On 9/2/10 12:36 PM, Don Pearce wrote:
Frank
Mobile Audio
You really can't think of absorbers as springs. Springs do not absorb
energy - they give back all of it. If they give it back with delay,
they are a huge problem. If they give it back with no delay, they are
purely elastic surfaces - tiles would be a good example. To kill
flutter echoes in a room, you have no choice - the energy must not be
returned along its incident path. You either absorb it, or let it out
into the outside where it can radiate. Both do an identical job, but
obviously with the second you do let the outside noise in.


I know that you're using springs as an analogy, but it reminded me that
I have like 3 queen sized mattresses and box-springs. Do these do
anything in terms of absorption? I'm just trying to think of things that
I already have which might be useful, which would free up my budget to
buy more acoustical material.

Thanks,
-Adam

[Frank Stearns]

adam79 writes:

On 9/2/10 12:36 PM, Don Pearce wrote:
Frank
Mobile Audio
You really can't think of absorbers as springs. Springs do not absorb
energy - they give back all of it. If they give it back with delay,
they are a huge problem. If they give it back with no delay, they are
purely elastic surfaces - tiles would be a good example. To kill
flutter echoes in a room, you have no choice - the energy must not be
returned along its incident path. You either absorb it, or let it out
into the outside where it can radiate. Both do an identical job, but
obviously with the second you do let the outside noise in.


I know that you're using springs as an analogy, but it reminded me that
I have like 3 queen sized mattresses and box-springs. Do these do
anything in terms of absorption? I'm just trying to think of things that
I already have which might be useful, which would free up my budget to
buy more acoustical material.

Not the most efficient in terms of room volume eaten up, and there might be a few
hiccups in terms of linearity, but sure, they're worth a try. The swept LF tones or
pink noise can tell you fairly clearly what effect those things are having.
Pump a tone into the room, find a really bad buildup, then tip a mattress
against the nearest wall or perhaps even the opposite wall and see what
happens. (Forget the box springs, though, and just use the mattresses.)

And speaking of big lumps of fiberous stuff... Haven't tried it personally, but some
folks have supposedly had success stacking insulation rolls in corners for LF
control. These are rolls of the pink stuff, designed to be unfurled into a wall
cavity. If you waited and got it on sale at the warehouse home improvement places,
you might get it for $10-12 roll.

Anyone done this?

Frank
Mobile Audio
--

[[email protected]]

On 2010-09-02 said:
I know that you're using springs as an analogy, but it reminded me
that I have like 3 queen sized mattresses and box-springs. Do
these do anything in terms of absorption? I'm just trying to think
of things that I already have which might be useful, which would
free up my budget to buy more acoustical material.
Not the most efficient in terms of room volume eaten up, and there
might be a few
hiccups in terms of linearity, but sure, they're worth a try. The
swept LF tones or
pink noise can tell you fairly clearly what effect those things are
having. Pump a tone into the room, find a really bad buildup, then
tip a mattress against the nearest wall or perhaps even the
opposite wall and see what happens. (Forget the box springs, though,
and just use the mattresses.)

I've used them for such a purpose to try to improve a bad
situation in an impromptu recording space. MIght not have
been ideal, but it was an improvement over what we had
without them grin.

And speaking of big lumps of fiberous stuff... Haven't tried it
personally, but some
folks have supposedly had success stacking insulation rolls in
corners for LF control. These are rolls of the pink stuff, designed
to be unfurled into a wall cavity. If you waited and got it on sale
at the warehouse home improvement places,
you might get it for $10-12 roll.
Anyone done this?
I've seen it done. ONly thing i"d suggest is keep folks
from coming in contact with the rolls, it's still itchy
fibrous stuff to come in contact with. There again,
iompromptu recording space, and the guy had it around for a
remodeling project.

Adam might want to look at Malcolm CHisholm's site, don't
have the url in front of me, but I asked for the location of
it since it wasn't at the old one in this group a year or so
ago. GOogle the name Adam. SOme great stuff on building
flats for absorption and/or reflection, whichever you need.
IF you haven't had a look at Malcolm's site there's some
ideas for you too.





Richard webb,

replace anything before at with elspider
ON site audio in the southland: see www.gatasound.com



Great audio is never heard by the average person, but bad
audio is heard by everyone.

[Bill Graham]

wrote in message
...

On 2010-09-02 said:
I know that you're using springs as an analogy, but it reminded me
that I have like 3 queen sized mattresses and box-springs. Do
these do anything in terms of absorption? I'm just trying to think
of things that I already have which might be useful, which would
free up my budget to buy more acoustical material.
Not the most efficient in terms of room volume eaten up, and there
might be a few
hiccups in terms of linearity, but sure, they're worth a try. The
swept LF tones or
pink noise can tell you fairly clearly what effect those things are
having. Pump a tone into the room, find a really bad buildup, then
tip a mattress against the nearest wall or perhaps even the
opposite wall and see what happens. (Forget the box springs, though,
and just use the mattresses.)

I've used them for such a purpose to try to improve a bad
situation in an impromptu recording space. MIght not have
been ideal, but it was an improvement over what we had
without them grin.

And speaking of big lumps of fiberous stuff... Haven't tried it
personally, but some
folks have supposedly had success stacking insulation rolls in
corners for LF control. These are rolls of the pink stuff, designed
to be unfurled into a wall cavity. If you waited and got it on sale
at the warehouse home improvement places,
you might get it for $10-12 roll.
Anyone done this?
I've seen it done. ONly thing i"d suggest is keep folks
from coming in contact with the rolls, it's still itchy
fibrous stuff to come in contact with. There again,
iompromptu recording space, and the guy had it around for a
remodeling project.

Adam might want to look at Malcolm CHisholm's site, don't
have the url in front of me, but I asked for the location of
it since it wasn't at the old one in this group a year or so
ago. GOogle the name Adam. SOme great stuff on building
flats for absorption and/or reflection, whichever you need.
IF you haven't had a look at Malcolm's site there's some
ideas for you too.

The most acoustically "dead" room I ever heard, was a computer room at
Stanford University where the guy in charge had hung acoustical adsorbing
tiles vertically from the ceiling every 4 feet or so, over the noise making
items in the room. (which at that time were the high speed printers) Before
then, I thought those tiles were supposed to be pasted on the walls....They
were 2 by 4 feet each, and this guy hung them vertically from the ceiling,
so they only cleared your head by about two feet or so.....Boy, was that
room DEAD!!

[adam79]

On 9/2/10 8:33 PM, Bill Graham wrote:

The most acoustically "dead" room I ever heard, was a computer room at
Stanford University where the guy in charge had hung acoustical
adsorbing tiles vertically from the ceiling every 4 feet or so, over the
noise making items in the room. (which at that time were the high speed
printers) Before then, I thought those tiles were supposed to be pasted
on the walls....They were 2 by 4 feet each, and this guy hung them
vertically from the ceiling, so they only cleared your head by about two
feet or so.....Boy, was that room DEAD!!

In alot of the stuff I've read/been reading, air space is a great sound
blocker.

[Arny Krueger]

"Frank Stearns" wrote in
message
And speaking of big lumps of fiberous stuff... Haven't
tried it personally, but some folks have supposedly had
success stacking insulation rolls in corners for LF
control. These are rolls of the pink stuff, designed to
be unfurled into a wall cavity. If you waited and got it
on sale at the warehouse home improvement places, you
might get it for $10-12 roll.

Household insulation has a nominal density of 2 pounds per cubic foot.

That $12 roll of insulation is 3 1/2 inches thick, and covers 40 square
feet, for a total volume of 11 cubic feet. It should weigh about 22 pounds
(unfaced). You are playing about $0.50 a pound for the fiberglass.

In comparison a package of 6 2' x 4' sheets of Dow Corning 703 insulation
board has a nominal density of 3 pounds per cubic foot. The package has a
volume of 8 cubic feet and should weigh about 24 pounds. It costs about $74
at a Dow Corning distributor. You're paying about $3 per pound for the
fiberglass.

If you could figure out how to compress the roll insulation by about 1/3 it
would work about as well as 703 for only a fraction of the price.

[Arny Krueger]

"adam79" wrote in message
net
On 9/2/10 8:33 PM, Bill Graham wrote:

The most acoustically "dead" room I ever heard, was a
computer room at Stanford University where the guy in
charge had hung acoustical adsorbing tiles vertically
from the ceiling every 4 feet or so, over the noise
making items in the room. (which at that time were the
high speed printers) Before then, I thought those tiles
were supposed to be pasted on the walls....They were 2
by 4 feet each, and this guy hung them vertically from
the ceiling, so they only cleared your head by about two
feet or so.....Boy, was that room DEAD!!

In alot of the stuff I've read/been reading, air space is
a great sound blocker.

No, air with fiberglass panels absorbs sound far better than just air.

[Frank Stearns]

"Bill Graham" writes:

snips

The most acoustically "dead" room I ever heard, was a computer room at
Stanford University where the guy in charge had hung acoustical adsorbing
tiles vertically from the ceiling every 4 feet or so, over the noise making
items in the room. (which at that time were the high speed printers) Before
then, I thought those tiles were supposed to be pasted on the walls....They
were 2 by 4 feet each, and this guy hung them vertically from the ceiling,
so they only cleared your head by about two feet or so.....Boy, was that
room DEAD!!

Great story. Those old computer rooms can really hurt your ears.

Place where I swim (room is 90 ft x 50 ft by 25 high) had to take out the rotting
insulation batts in the ceiling and build a new roof over the old one and insulate
between the two.

But now we had a big cavern, with hard surfaces everywhere.

The RT60 went up to over 11 seconds (measured by their acoustician).

Patrons and owner agreed it was intolerable. Imagine a bunch of screaming kids; but
even the splash sounds of adult lap swimming was ear shattering.

The eventually hung, on the verticle, fifty or sixty 2'x4' sheets of styrofoam-like
material, about 2 inches thick, pressed with traditional anachoic wedge shapes
alternating 90 degrees; probably a 100 or so wedge clusters per sheet. One side was
an "innie", the other side was an "outie" of the wedge contours.

I was happily amazed. RT60 went down to just a little over 2 seconds. Much more
pleasant!

It's amazing what you can do if you stop the energy from rolling around and around
and around... And in this case, you only needed to capture it on one plain.

Frank
Mobile Audio

--

[Frank Stearns]

"Arny Krueger" writes:

"Frank Stearns" wrote in
message
And speaking of big lumps of fiberous stuff... Haven't
tried it personally, but some folks have supposedly had
success stacking insulation rolls in corners for LF
control. These are rolls of the pink stuff, designed to
be unfurled into a wall cavity. If you waited and got it
on sale at the warehouse home improvement places, you
might get it for $10-12 roll.

Household insulation has a nominal density of 2 pounds per cubic foot.

That $12 roll of insulation is 3 1/2 inches thick, and covers 40 square
feet, for a total volume of 11 cubic feet. It should weigh about 22 pounds
(unfaced). You are playing about $0.50 a pound for the fiberglass.

In comparison a package of 6 2' x 4' sheets of Dow Corning 703 insulation
board has a nominal density of 3 pounds per cubic foot. The package has a
volume of 8 cubic feet and should weigh about 24 pounds. It costs about $74
at a Dow Corning distributor. You're paying about $3 per pound for the
fiberglass.

If you could figure out how to compress the roll insulation by about 1/3 it
would work about as well as 703 for only a fraction of the price.


Aye, there's the rub (or itch, as the case might be). 700 series is way more space
efficient, both for acoustic use and insulating purposes.

Now, if you leave the roll insulation bundled, there is some compression that has
already taken place. The near 2 foot diameter of the roll should do something in a
corner to help with LF.

As far as compressing it to 1/3 for the same performance as 703... Not so sure about
that -- not entirely sure that the relationship is linear (compression v.
performance). The relationship might be leaning more toward log or "hocky stick"?
Don't know, just asking.

Also, have no way to know, but perhaps the geometry of the fiber particles (or
particle clumps) differs between what's used to make the batt and pressed forms?

Interesting discussion.

Frank
Mobile Audio
--

[PStamler]

On Sep 2, 8:22*pm, Frank Stearns
wrote:

Now, if you leave the roll insulation bundled, there is some compression that has
already taken place. The near 2 foot diameter of the roll should do something in a
corner to help with LF.

Put some cloth around it and some ends on it, and you've invented Tube
Traps.

Peace,
Paul

[Frank Stearns]

PStamler writes:

On Sep 2, 8:22=A0pm, Frank Stearns
wrote:

Now, if you leave the roll insulation bundled, there is some compression =
that has
already taken place. The near 2 foot diameter of the roll should do somet=
hing in a
corner to help with LF.

Put some cloth around it and some ends on it, and you've invented Tube
Traps.

Pretty close. The DIY tube traps we've done here use Owens-Corning 703 in an
industrial pipe insulation format. You can get 3 foot lengths of pipe sleeving
(clamshell configuration) with wall thicknesses of 1", 2" or 3", with inside
diameters from 6" to 24" and probably other sizes as well. We used mostly 12" ID, 2"
wall, some 16" ID as well.

Cap both ends with 3/4" MDF (loose partial fill with chunks of batt insulation), and
you have a fairly good tube trap. Use the faced version of the pipe insulation to
provide some MF and HF reflection if desired; the round shape gives some flavor
of diffusion.

Just like the panel traps, make sure the caps and tube are reasonably air tight. My
trick was to center up holes in the MDF caps and then in the ends of 1 1/4" dowel
(closet rod stock) slightly shorter then the pipe insulation length. Screw the
dowel on one cap, drop on and center the sleeve, loose fill with batt insulation if
desired, then fit the other cap. Again be careful about over tensioning, otherwise
the insulation walls can start to resonate.

They don't seem quite as effective as panel traps but they make up for it by being
portable, and they do look cool, if you can find a nice or interesting colored cloth
to use for a wrap.

Frank
Mobile Audio
--

[Arny Krueger]

"Bill Graham" wrote in message


I hope the new styrofoam material was moisture
proof/resistant....Strikes me that mould would be a
problem with most materials in an atmosphere like that.

More to the point, hopefully it was fire resistant.

Lately we seem to have experienced a goodly number of unfortunate deaths due
to people obtaining good sound along with considerable risk of catastrophic
fire.